page_title: Geology of Ontario
section_title: Niagara Falls
hierarchical_section_title: Geology of Ontario / Wisconsin glaciation / Niagara Falls
caption_attribution_description: The Niagara Falls are voluminous waterfalls on the Niagara River, straddling the international border between the Canadian province of Ontario and the U.S. state of New York. The falls are 17 miles (27 km) north-northwest of Buffalo, New York and 75 miles (120 km) south-southeast of Toronto, Ontario, between the twin cities of Niagara Falls, Ontario, and Niagara Falls, New York. Niagara Falls is composed of two major sections separated by Goat Island: Horseshoe Falls, the majority of which—two-thirds according to the US Geological Survey—lies on the Canadian side of the border, and American Falls on the American side. The smaller Bridal Veil Falls are also located on the American side, separated from the main falls by Luna Island. Niagara Falls were formed when glaciers receded at the end of the Wisconsin glaciation (the last ice age), and water from the newly formed Great Lakes carved a path through the Niagara Escarpment en route to the Atlantic Ocean. While not exceptionally high, the Niagara Falls are very wide. More than 6 million cubic feet (168,000 m³) of water falls over the crest line every minute in high flow, and almost 4 million cubic feet (110,000 m³) on average. It is the most powerful waterfall in North America. The Niagara Falls are renowned both for their beauty and as a valuable source of hydroelectric power. Managing the balance between recreational, commercial, and industrial uses has been a challenge for the stewards of the falls since the 19th century. Niagara Falls is divided into the Horseshoe Falls and the American Falls. The Horseshoe Falls drop about 173 feet (53 m), the height of the American Falls varies between 70–100 feet (21–30 m) because of the presence of giant boulders at its base. The larger Horseshoe Falls are about 2,600 feet (790 m) wide, while the American Falls are 1,060 feet (320 m) wide. The volume of water approaching the falls during peak flow season may sometimes be as much as 202,000 cubic feet (5,700 m3) per second. Since the flow is a direct function of the Lake Erie water elevation, it typically peaks in late spring or early summer. During the summer months, 100,000 cubic feet (2,800 m3) per second of water actually traverses the Falls, some 90% of which goes over the Horseshoe Falls, while the balance is diverted to hydroelectric facilities. This is accomplished by employing a weir with movable gates upstream from the Horseshoe Falls. The Falls flow is further halved at night, and during the low tourist season in the winter, remains a flat 50,000 cubic feet (1,400 m3) per second. Water diversion is regulated by the 1950 Niagara Treaty and is administered by the International Niagara Board of Control (IJC). Viewpoints on the American shore generally are astride or behind the falls. The falls face directly toward the Canadian shore. en.wikipedia.org/wiki/Niagara_Falls en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_...
context_page_description: The geology of Ontario consists of the study of the rock formations in the most populated province of Canada. Ontario has some of the oldest rocks on Earth. It is made up of ancient Precambrian igneous and metamorphic rock and overlain by younger sedimentary rocks and soils.
  About 61% of the province is covered by the Canadian Shield. The shield can further be divided into three sections or provinces. The northwestern parts of the Shield, located roughly north and west of Sudbury, are known as the Superior province is the largest of the three sections, covering about 70% of the Shield portion in Ontario. The Southern province is a narrow region from Sault Ste. Marie to Kirkland Lake. The South central part is dominated by the Grenville Province but flanked by two basins of Phanerozoic materials.
  World-class mineral deposits can be found here and are mined extensively.
context_section_description: The features that became Niagara Falls were created by the Wisconsin glaciation about 10,000 years ago. The same forces also created the North American Great Lakes and the Niagara River. All were dug by a continental ice sheet that drove through the area, deepening some river channels to form lakes, and damming others with debris.
  When the ice melted, the upper Great Lakes emptied into the Niagara River, which followed the rearranged topography across the Niagara Escarpment. In time, the river cut a gorge through the north-facing cliff, or cuesta. Because of the interactions of three major rock formations, the rocky bed did not erode evenly. The top rock formation was composed of erosion-resistant limestone and dolomite of the Lockport Formation. That hard layer of stone eroded more slowly than the underlying materials.
  Immediately below the hard-rock formation, comprising about two-thirds of the cliff, lay the weaker, softer, sloping Rochester Formation (Lower Silurian). This formation was composed mainly of shale, though it has some thin limestone layers. It also contains ancient fossils. In time, the river eroded the soft layer that supported the hard layers, undercutting the hard caprock, which gave way in great chunks. This process repeated countless times, eventually carving out the falls.
  Submerged in the river in the lower valley, hidden from view, is the Queenston Formation (Upper Ordovician), which is composed of shales and fine sandstones. All three formations were laid down in an ancient sea, their differences of character deriving from changing conditions within that sea.
  About 10,900 years ago, the Niagara Falls was between present-day Queenston, Ontario, and Lewiston, New York, but erosion of their crest has caused the waterfalls to retreat approximately 6.8 miles (10.9 km) southward. The Horseshoe Falls, which are about 2,600 feet (790 m) wide, have also changed their shape through the process of erosion; evolving from a small arch to a horseshoe bend, to the present day gigantic V. Just upstream from the falls' current location, Goat Island splits the course of the Niagara River, resulting in the separation of the mostly Canadian Horseshoe Falls to the west from the American and Bridal Veil Falls to the east. Engineering has slowed erosion and recession.
  The current rate of erosion is approximately 30 centimeters (1 ft) per year, down from a historical average of 0.91 m (3 ft) per year. According to the timeline of the far future, in roughly 50,000 years Niagara Falls will have eroded the remaining 32 kilometres (20 mi) to Lake Erie and ceased to exist.
caption: Niagara Falls
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